fix(a11y): new color contrasts

[biou]

related to #419

This is just a proposal. The idea is to have contrasts > 4.5:1 which is not currently the case. Currently people can have difficulties to see that there is a button and click on it.
For the hover/active state, instead of changing the color, we could also consider animating the dots.

[codecov-commenter]

Codecov Report

Merging #429 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #429   +/-   ##
=======================================
  Coverage   96.59%   96.59%           
=======================================
  Files           8        8           
  Lines         382      382           
  Branches       53       53           
=======================================
  Hits          369      369           
  Misses         13       13           

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[goblindegook]

I'd probably make this a breaking change (just add BREAKING CHANGE: before the commit description) since it would change button colours for current users who haven't customised/overridden their styles.

[biou]

Anything I can do to improve this PR @goblindegook ?

[goblindegook]

Haven't forgotten about it. I was considering batching this with some other breaking changes, possibly an overhaul of the styles (which were left mostly unchanged from Bigfoot), dropping Sass and adding support for stuff like CSS variables.

[biou]

No problem, sounds good!

[goblindegook]

Closing the PR because these files no longer exist. Changes will incorporate the feedback discussed in #419.